Waste-liquor burner and disperser

ABSTRACT

The invention relates to a device for burning waste liquor and to the disperser in the form of a nozzle used therein. The liquor is dispersed downwards from the corners of a furnace in showers of droplets in the form of full cones. The distance of the dispersers nozzle outlets from the bottom of the furnace is 45-60 percent of the sum of a narrower and a broader side of the furnace&#39;&#39;s bottom plane and the geometrical axis of each of the dispersers is in a plane which forms an angle of 40* -50* with the sidewalls of the furnace, and the axis of each disperser forms an angle of 35* -55* with the vertical line of intersection of the furnace sidewalls. The top angle of the outlet in the outlet member is 60* -90* and the diameter of the outlet is 30-45 percent of the inner diameter of the nozzle body. The body of the nozzle comprises a detachable vortex element having four spiral grooves at an angle of 45* -60* to the transverse axis of the nozzle. The crosssectional flow area of the grooves is 45-55 percent of the inner cross-sectional area of the nozzle body portion.

United States Patent Reino T. Huouvilainen Kaleva, Finland 80 1,049

Inventor [21 1 Appl. No. [22] Filed Feb. 20, 1969 [45] Patented Apr. 13, 1971 [73] Assignee 0y Tampelia Ab ABSTRACT: The invention relates to a device for burnin erein. The liquor is dispersed downwards from the comers of a furnace in showers of droplets in the form of full cones. The distance of the dispersers nozzle outlets from the bottom of the furnace is 45 --60 percent of the sum of a narrower and angle of 4050 with the sidewalls of the furnace axis of each disperser forms an an tical line of intersection of the fu The top angle of the outlet in the outlet member is 60-90 and the diameter of the outlet is 30-45 diameter of the nozzle body. The bod a detachable vortex element havin angle of 4560 to the transverse axis of the nozzle. The

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2. Description of the Prior Art Several methods of burning black liquor are prior known:

the commonest method is to spray the liquor into the furnace by means of a disperser swinging in a vertical plane, On leaving the disperser, the liquor fans out and disperses into droplets of varying sizes. The disperser is designed so that the spray of liquor is directed obliquely upwards. The object of the swinging motion of the disperser is to ensure an even distribution of liquor droplets over the cross-sectional area of the soda-boiler furnace. For the same purpose, two or more dispersers are fitted on two opposite walls of the boiler and are made to swing either synchronously or asynchronously.

In another method, dispersers of the above type are also made to swing to and fro in a circular movement around their axes, the object being to promote an evener distribution of liquor droplets on the cross-sectional area of the furnace.

In a method differing in principle from the above two, the liquor is sprayed onto the walls of the soda boiler, either by dispersers swinging to and fro in a vertical plane, or by liquor guns." In this case, most of the liquor is dried and burned on the walls of the boiler.

Recently, the liquor has been sprayed straight downwards by centrifugal dispersers fitted in the middle of the furnace. The nozzles, usually numbering one or two, disperse the liquor droplets in the form of hollow cones. In this method the droplets are fairly small in size.

SUMMARY OF THE INVENTION The invention relates to a device for burning waste liquor, particularly black liquor resulting from the cooking of sulfate cellulose, in which there are several dispersers formed as nozzles attached to a boiler furnace, wherein the dispersers are fitted in the comers of the said furnace or in their immediate vicinity in such a way that the liquor is dispersed obliquely downwards in showers of droplets, shaped in the form of full cones. The distance of the nozzle outlets from the bottom plane of the boxlike furnace is from 4560 percent of the sum of a longer and a shorter side of the quadrangular furnace bottom. The furnace sidewalls are vertically oriented and the geometrical axis of each of the dispersers lies in a pane fomting an angle of 40-50 with the adjacent sidewalls of the furnace. The axis of each disperser nozzle also forms an angle of 355S with the vertical line of intersection of the adjacent furnace walls.

The object of the invention is to reduce the depositing of impurities on the heat surfaces and to improve the recovery of inorganic substances from the liquor in boilers for the recovery of heat and chemicals which employ waste liquor as their fuel.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I, the boxlike furnace is shown to have a rectangular base with a pair of opposed broader side edges and a pair of opposed narrower edges. There are four vertical sidewalls, two of which are narrower than the other two. The furnace walls have three arrays of air nozzles, the primary air nozzles 5, secondary air nozzles 3, and tertiary air nozzles 4 arranged as shown in the drawing. A stack of hotsolid material rests at the bottom of the furnace as shown at 2. The method of reducing depositing of inpurities on the heat surfaces of the boiler can be described in two ways:

a. The unburned liquor droplets are not taken to the upper part of the furnace by the waste gases because, when they fall through the space between the tertiary 4 and secondary 3 air nozzles, in which the flow of waste gases is quicker than it is between the secondary 3 and primary 5 air nozzles, only a little of the water in the droplets has evaporated and their density is so great that the lifting force of the waste-gas flow is unable to halt their downward movement. In the next phase of droplet fall, that between the secondary 3 and primary 5 air nozzles, the droplets expand owing to the rapid evaporation of water on their surface, and partly, too, in their interior, while the evaporation of the water and partial pyrolysis of the organic substances in them reduces their mass. This increases the effect of the lifting force of the waste-gas flow. However, owing to the high speed of the droplets and low speed of the waste gases during this stage, the droplets finally fall to the surface of the stack 2. It should be noted that, in this invention, every droplet of liquor falls almost the same distance to the stack whereas, when swinging dispersers are used, for instance, the distance the droplets fall when the disperser is in its upper position is many times the distance they fall when the disperser is in its lower position. For this reason, the smallest droplets sprayed by a swinging disperser are bound to fly upwards with the waste gases, and deposit impurities on the heating surfaces, when the disperser is in its upper position.

b. The quantity of inorganic substances lost with the waste gases owing to sublimation is reduces by suitably adjusting the angle of the disperser I and the size of the droplets. Thanks to the former, the entire surface of the stack 2 is irrigated by a fairly cool rain of droplets, so that the substances sublimated by the hot surface of the stack condense on the surface of the liquor droplets. On the other hand, it is an advantage to select a large size for the droplets because the sublimation occurring at the hot points of large droplets is less in ratio to the mass of the liquor than it is in small droplets.

The burning device in this invention also reduces the chemical losses because the quantity of organic carbon eliminated by pyrolysis from the surface of the droplets during their fall is smaller than it is, for example, in a swinging disperser. This is due to the obvious fact that pyrolysis is more intensive at high temperatures. In the method according to this invention, in which the distance the droplets fall to the surface of the stack 2 is almost uniform, the temperature is practically the same on the surface of all the droplets, and as this temperature can be adjusted by modifying the size of the droplets and the distance they fall, the result achieved is pyrolysis of only a small quantity of organic carbon. This low pyrolysis increases the proportion of carbon reaching the surface of the stack, which promotes the chemical reaction of the inorganic substances in the liquor and thus aids the recovery of chemicals.

Another chemical improvement will become clear from FIG. 1: in other burning devices, the stack usually burns quickest in the comers of the furnace, which raises the temperature of the stack, thus increasing the sublimation of inorganic substances and deteriorating the recovering of chemicals, especially if, as usually happens, there is too much air. In the burner according to this invention, the density of the liquor mass on the surface of the stack 2 is greatest in the corners of the furnace, which reduces this disadvantage.

As can be seen in FIGS. 2 and 3, the nozzle outlet member 7 is fitted in the body 6 of the nozzle 1. The internal conical angle of the frustoconical hole in the outlet member is 60: 90 and the diameter of its outlet 9 is 30-45 percent of the inner diameter of the nozzle body. Inside the body is fitted a detachable vortex element 8, furnished with four spiral grooves at an angle of 45-60 to the transverse axis of the nozzles in such a way that the cross-sectional flow area of the grooves is 45-55 percent of the inner cross-sectional are of the nozzle body. A nozzle of this type assures an advantageous dispersion angle and droplet size.

A suitable nozzle 1 emits liquor droplets of such size that, by the time they fall to the stack 2 formed at the bottom of the boiler furnace, they are almost dry, which is a prerequisite for burning the organic part of the dry matter in the liquor and for reacting the inorganic part of the liquor on the surface of the stack.

lclaim:

1. Apparatus for burning waste liquor, particularly black liquor resulting from the cooking of sulfate cellulose, in which there are several nozzles attached to a boiler furnace which has a boxlike shape with a generally rectangular bottom and opposed pairs of sidewalls, one pair of the walls being relatively broader and the other pair of walls being relatively narrower, wherein the nozzles are fitted adjacent upper corners of the furnace in such a way that the liquor is dispersed obliquely downwards in showers of droplets, the showers being shaped in the form of full cones, the distance of outlets of said nozzles from the bottom of said furnace being 45-60 percent of the sum of the widths of a narrower sidewall and a broader sidewall of the furnace measured at the furnace bottom, a geometrical axis of each of the nozzles lying in a plane forming an angle of 4050 with the adjacent sidewalls of the furnace, and the axis of each nozzle forming an angle of 35J -55 with the vertical line of intersection of said adjacent sidewalls.

2. Apparatus according to claim 1, wherein each nozzle comprises a body portion and an outlet member having a hole of frustoconical shape, the hole having a top angle of 6090 and the diameter of the outlet being 3045 percent of the inner diameter of the body portion.

3. Apparatus according to claim 2 wherein the nozzle is fitted internally with a detachable vortex element having four spiral grooves lying at an angle of 4560 to the transverse axis of said nozzle body portion in such a way that the crosssectional flow area of the grooves is 4555 percent of the inner cross-sectional area of the nozzle body. 

2. Apparatus according to claim 1, wherein each nozzle comprises a body portion and an outlet member having a hole of frustoconical shape, the hole having a top angle of 60*-90* and the diameter of the outlet being 30-45 percent of the inner diameter of the body portion.
 3. Apparatus according to claim 2 wherein the nozzle is fitted internally with a detachable vortex element having four spiral grooves lying At an angle of 45*-60* to the transverse axis of said nozzle body portion in such a way that the cross-sectional flow area of the grooves is 45-55 percent of the inner cross-sectional area of the nozzle body. 